Cancelling an active backup now works properly when multiple online disks are connected

Improved the installation experience on Ubuntu 11.04. Note that it is safe to proceed with installation if you receive a "The package is of bad quality" message. This is a known issue with Ubuntu (see https://bugs.launchpad.net/ubuntu/+source/software-center/+bug/712377 )

Reduced memory usage when executing a backup vault cleanup.

Corrected an issue that could cause missed backups to not execute, even when the "run missed backups as soon as possible" option was set

Corrected an issue that could cause scheduled backup jobs to occassionaly run twice